Ammonia flux, physiological parameters, and Symbiodinium diversity in the anemonefish symbiosis on Red Sea coral reefs

Modi Roopin, Daniel J. Thornhill, Scott R. Santos, Nanette E. Chadwick

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Despite the ecological importance of anemonefish symbioses, little is known about how nutritional contributions from anemonefish interact with sea anemone physiology and Symbiodinium (endosymbiotic dinoflagellate) genetic identity under field conditions. On Red Sea coral reefs, we measured variation in ammonia concentrations near anemones, excretion rates of anemonefish, physiological parameters of anemones and Symbiodinium, and genetic identity of Symbiodinium within anemones. Ammonia concentrations among anemone tentacles were up to 49% above background levels, and anemonefish excreted ammonia significantly more rapidly after diurnal feeding than they did after nocturnal rest, similar to their excretion patterns under laboratory conditions. Levels of 4 physiological parameters (anemone protein content, and Symbiodinium abundance, chlorophyll a concentration, and division rate) were similar to those known for laboratory-cultured anemones, and in the field did not depend on the number of anemonefish per anemone or depth below sea surface. Symbiodinium abundance varied significantly with irradiance in the shaded reef microhabitats occupied by anemones. Most anemones at all depths harbored a novel Symbiodinium 18S rDNA variant within internal transcribed spacer region 2 (ITS2) type C1, while the rest hosted known ITS2 type C1. Association with Symbiodinium Clade C is consistent with the symbiotic pattern of these anemones on other Indo-Pacific reefs, but the C1 variant of Symbiodinium identified here has not been described previously. We conclude that in the field, anemonefish excrete ammonia at rapid rates that correlate with elevated concentrations among host anemone tentacles. Limited natural variation in anemonefish abundance may contribute to consistently high levels of physiological parameters in both anemones and Symbiodinium, in contrast to laboratory manipulations where removal of fish causes anemones to shrink and Symbiodinium to become less abundant.

Original languageEnglish
Pages (from-to)63-74
Number of pages12
JournalSymbiosis
Volume53
Issue number2
DOIs
StatePublished - May 2011
Externally publishedYes

Bibliographical note

Funding Information:
We thank Baraka Kuguru for field assistance, and Mark Liles, Dusty Kemp, and Greg Schmidt for assistance with DGGE analysis. Joseph Szczebak created the artwork for Fig. . Funding was provided by start-up funds to NEC and a graduate research award to MR, both from Auburn University. This research is submitted in partial fulfillment of the requirements for a M.Sc. degree to MR at Auburn University. All sampling for this study complies with the current laws of Israel. This is contribution #51 of the Auburn University Marine Biology Program.

Funding

We thank Baraka Kuguru for field assistance, and Mark Liles, Dusty Kemp, and Greg Schmidt for assistance with DGGE analysis. Joseph Szczebak created the artwork for Fig. . Funding was provided by start-up funds to NEC and a graduate research award to MR, both from Auburn University. This research is submitted in partial fulfillment of the requirements for a M.Sc. degree to MR at Auburn University. All sampling for this study complies with the current laws of Israel. This is contribution #51 of the Auburn University Marine Biology Program.

FundersFunder number
Auburn University

    Keywords

    • Dinoflagellate
    • Fish
    • Mutualism
    • Nutrient
    • Sea anemone
    • Symbiodinium

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